package Utils;

import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/*
        JDBC工具类
*/
public class JDBCUtils {
        //1.私有构造方法
        private JDBCUtils(){};

        //2.声明配置信息变量
        private static String driverClass;
        private static String url;
        private static String username;
        private static String password;
        private static Connection con;
    private static Statement stat;
    private static ResultSet rs;

    //3.静态代码块中实现加载配置文件和注册驱动
        static{
            try{
                //通过类加载器返回配置文件的字节流
                InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("config.properties");

                //创建Properties集合，加载流对象的信息
                Properties prop = new Properties();
                prop.load(is);

                //获取信息为变量赋值
                driverClass = prop.getProperty("driverClass");
                url = prop.getProperty("url");
                username = prop.getProperty("username");
                password = prop.getProperty("password");

                //注册驱动
                Class.forName(driverClass);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        //4.获取数据库连接的方法
        public static Connection getConnection() {
            try {
                con = DriverManager.getConnection(url,username,password);
            } catch (SQLException e) {
                e.printStackTrace();
            }

            return con;
        }

        //5.释放资源的方法
        public static void close(Connection con, Statement stat, ResultSet rs) {
            JDBCUtils.con = con;
            JDBCUtils.stat = stat;
            JDBCUtils.rs = rs;
            if(con != null) {
                try {
                    con.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

            if(stat != null) {
                try {
                    stat.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }

            if(rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }

        public static void close(Connection con, Statement stat) {
            close(con,stat,null);
        }
    }

